Psh. There have been MANY sentai character songs where they couldn't sing. Off the top of my head, I can think of DekaRed's, MagiRed's, and MagiGreen's. They were horrid. I wish he would have done it either way. I hate his song right now.
Plus, Genta isn't all that great either. The song, yes. His voice? Not amazing.
Kamen Rider OOO, Kaizoku Sentai Gokaiger
Digimon Tamers, VR Troopers